Some of the egg-producing hens were caged above manure pits four to eight feet deep. The weight of these vast manure pits had burst open outside doors.

In several locations at both Iowa firms -- Quality Egg (also doing business as Wright County Egg) and Hillandale Farms -- inspectors culled samples of Salmonella Enteritidis. These samples had the same DNA fingerprint seen in patients sickened in the ongoing salmonella outbreak traced to eggs.

It's not clear what action the FDA will take. While the company that owns the farms is not selling shell eggs to consumers, it continues to sell eggs to food makers who sterilize the eggs during processing.

What is clear is that the FDA is immediately launching a program to inspect all large U.S. egg farms. There are more than 600 such facilities, each with at least 50,000 or more laying hens. Such farms produce about 80% of all U.S. eggs.

The conditions at the Iowa farms seem horrible. But during a brief press teleconference held to announce the release of the inspection reports, FDA officials refused to say whether the findings are uncommon at large egg-producing facilities.

Michael R. Taylor, JD, FDA deputy commissioner for foods, said only that the inspections document violations of the FDA's new "egg rule," which took effect on July 9 -- well after the current salmonella outbreak began.

"The observations speak for themselves," Michael R. Taylor, JD, FDA deputy commissioner for foods, said at the news conference. "The presence of rodents is objectionable. We made these observations because there are significant deviations from the egg rule."

Among other things, FDA investigators found:

Huge manure pits open to outside animals.

Evidence that rodents, wild birds, and other animals could enter the henhouses via missing siding and gaps in doors and walls.

So many live flies that they were crushed underfoot on walkways. Maggots "too numerous to count" were seen in at least one manure pit.

Farm workers went from henhouse to henhouse without cleaning their tools or changing their shoes or clothing -- which can spread germs between houses.

Uncaged birds tracked manure from the pits to the laying houses.

"The firms have informed FDA that they will not ship eggs to consumers until the FDA is satisfied it is safe to do so," David Elder, FDA director of regional operations, said at the news conference.

The salmonella outbreak has sickened thousands of people across the nation. It's not yet clear whether the outbreak is over, as there is a delay between the time a person falls ill and the time the case is reported. But there have been no new clusters of illness. Moreover, no cases have been traced to eggs from firms other than Wright County/Quality Egg and Hillandale Farms.